Lapping machine



June 29, 1937.

R. A. COLE 2,035,005

LAPPING MACHINE Filed July 6, 1936 2 Sheets-Sheet l 9% Mum June 29, 1937. R, A. COLE LAPPING MACHINE Filed July 6, 1956 2 Sheets-Sheet 2 7/ Ema/whom FPHYMUND ADELE Fl'gZ Patented June 29, 1937 7 2,085,005 I LAPPING MACHINE Raymond A. Cole, Worcester, Mass., assignor to Norton Company, Worcester, Mass., a corporation of Massachusetts Application July 6, 1936, Serial No. 88,955

12 Claims.

This invention relates to lapping machines, and i more particularly to an improved automatically operated lapping machine.

One object of this invention is to provide a 5 simple, thoroughly practical lapping machine in which therelative approaching movement of the lapping elements is automatically controlled. Another object of this invention is to,.provide a lapping machine in which the lapping elements 10 are moved relatively toward each other for a given lapping operation and after .a predetermined interval of lapping are automatically sep- -arated.- A further object of this invention is to provide a lapping machine in which the lapping 5 elements are caused to move relatively into operativelapping engagement with the work pieces at a relatively high pressure for a predetermined time interval, after which the pressure is auto- 'matically reduced to permit a finish lapping op- 20 eration for a predetermined period.

A further object .of' this invention is to provide an automatic control device for a lapping machine which moves the lapping elements into lapping engagement with the work pieces and auto- 25 matically applies a predetermined pressure to rough lap the work pieces for a definite time interval, after which the pressure is reduced to a finish lapping pressure and the lapping operation continues for a further predetermined period,

. after which the lapping elements are automatically separated and the relative rotation thereof is stopped. Other objects will be in part obvious or in part pointed out hereinafter.

The invention accordingly consists in the fea- 35 tures of construction, combinations of elements, and arrangements of parts, as will be exemplified in the structure to be hereinafter described, and the scope of the application of which will be indicated in the following claims. 40 'In the accompanying drawings in which is shown one of various possible embodiments of the mechanical features of this invention,

Fig. l is a diagrammatic view, showing the.

drive for the lapping wheels and the cage and the 5 hydraulic system for controlling the relative approaching and receding movement of the laps as well as an electrical wiring diagram for controlling the fiuid pressure system; and

Fig. 2 is a side elevation of an improved lapping machine, having parts broken away and shown in section to more clearly show the construction.

A lapping machine has been illustrated in the drawings comprising a base In which supports a 55 rotatable spindle H which in turn supports a spider |2 at its upper end. The spider |2 supports a lapping wheel mounting plate |3 which in turn supports a lapping wheel l4. The base I0 is provided with an upwardly extending column l5 which supports a rotatable, vertically movable spindle IS. The lower end of the spindle I6 is provided with a wheel supporting plate I! which is arranged to support a lapping wheel I8 in opposed relation to the lapping wheel H. The lapping wheels l4 and iii are arranged for a relative rotary motion as well as a relative approaching and receding movement to produce the desired lapping operation.

In the preferred construction, the upper lapping element or wheel I8 is arranged for a rotary and relative approaching and receding movement. The spindle I6 is supported in anti-friction bearings 20 and 2| which are in turn supported in a vertically slidable sleeve 22. The-upper end 23 of the spindle is slidably keyed to a driving pulley 24 which is connected by driving belts 25 to a pulley 26 supported on the upper end of a rotatable shaft 21. An electric motor 30 is provided with a driving pulley 3| and is connected by a belt 32 with a pulley 33 which is rotatably supported on a shaft 34. The shaft 34 carries a worm 40 which meshes with a worm gear 4| mounted on the lower end of a rotatable shaft 42. The shaft 42 is connected by a universal joint.43 with a telescopic shaft 44. The telescopic shaft 44 is in turn connected with a universal joint 45 with the lower end of the rotatable shaft 21. It will be readily apparent from the foregoing construction that when the shaft 34 is rotated, a rotary motion will be transmitted through the worm 40, the worm gear 4|, the shaft 42, the universal joint 43, the telescopic shaft 44, the universal joint 45, the shaft 21, the pulley 26, the belt 25, the pulley 24, to rotate the spindle l6 and thereby transmit the desired rotary motion to the upper lapping wheel Similarly, the shaft 34 carries a worm 50 which meshes with a worm gear 5| mounted on the lower end of the spindle I I so that when the shaft 34 is rotated, a rotary motion is transmitted through the worm 50, the worm gear 5| and the spindle II to rotate the lower lapping element H ,at the desired speed.

In order to facilitate stopping and starting of the machine as desired, a suitable clutch is provided. An internal cone-shaped clutch member 60 is formed within the driving pulley 33 and an external cone clutch member 6| is keyed to the shaft 34. When the clutch member 6| is thrown toward the right (Fig. 2) into engagement with the clutch member 60, the rotary motion of the pulley 33 will be transmitted to the shaft 34 to drive the upper lap I8 and lower lap I4 at the desired and predetermined speed. Inorder to facilitate actuation of the clutch,the clutch member BI is provided with an integral grooved member 62 which is engaged by a movable arm 63.-

The arm 63 is supported on a slidable rod 64 which is arranged to be moved longitudinally by means of a manually operable control lever 65, which is pivotally supported on a stud'66' on the base I0. The lower end of the lever 65 is connected by a stud 61 with one end of a link 68.

The other end of the link 68 is connected by a stud 69 with the end of the slidably mounted rod 64. The rod 64 is slidably mounted in bearings 10 and II on the base I0. I

In order to hold the clutch member 6I in an operative or inoperative position, an arrow point I2 is mounted on the upper end of the arm 63 and is arranged to be engaged by a springpressed roller I3 which serves to hold the clutch either in driving engagement or disengaged, as

illustrated in Fig. 2.

It is desirable to provide a braking member so that when the clutch member 6| is disengaged from the clutch member 60, the rotation of the .lapping wheels will be immediately stopped. This is preferably accomplished by providing a brakingelement I4 which is fixedly mounted on the movable clutch member GI and which is arranged to engage a stationary brake disk I5 which is fixedly mounted on the base I0. When the clutch member 6| is disengaged, the brake disk I4 is moved into engagement with the fixed brake, disk 'I5.to immediately stop the rotation of the shaft 34 and thereby stop the rotation of the lapping elements I4 and I8 respectively.

A plurality of work pieces 80 are mounted in an aperture in a work carrying cage 8I which is carried by driving pins 82 which are rotated and revolved by means of a gear mechanism 83. See, for example, the cage operating mechanism disclosed in the prior United States patent 5 to Indge. No. 1,610,527 dated December 14, 1926.

I ,This cage operating mechanism is not apart of proach' or recede from been illustrated in the present invention and consequently has not detail. For further reference to the cageoperating mechanism, reference may be had'to the above-mentioned patent.

'The upper lapping wheel may be moved vertically to cause the lapping wheel I8 to apthe wheel I4 by means of a hand wheel (not shown) mounted on the outer end of a rotatable shaft 90. The shaft 90 carries a gear 91 meshing with a 'rack bar 92 mounted on the rear of the vertically movable sleeve 26. A counterbalance mechanism is provided to counterbalance'the'weight of the upper lapping wheel. I 8. Thisicomprises an adjustable weight'95 suspended by a link chain 96 which passes over an idler sprocket 91 which is rotatably mounted on a stud 98 carried by an adjustable bell crank arm 99. A link chain I passes over an end portion of the sprocket 91 and also over a sprocket raising and lowering the upper lap in order that a predetermined and controlled pressure may be applied between the lapping elements and able sleeve 22.

' I28. In the position of the lol carried by the shaft 90 so that theweight of the movable lap and its associated parts is counterbalanced, thereby fa-- the work and also in order that the'cycle of movement may be readily controlled. A pair of diametrically opposed cylinders H0 and III are supported on the frame of the machine on diametrically opposite sides of the vertically mov- The cylinders contain slidably mounted pistons H2 and H3 respectively which are connected by piston rods H4 and H5 respectively with a bracket I I6 which is supported at the lower end of the slidably mounted sleeve 22 so that a fluid pressure movement of the upper lapping element causes a "vertical ape proaching or receding movement at the upper lap I8 and applies a substantially uniform pressure at diametrically opposite sides of the lapping element so asto cause a substantially uniform pressure at all points between the lapping elements I4 and I8 and the work pieces 80.

Fluid under pressure is supplied from a reservoir I20 which is preferably located within the base of the machine. A fluid pressure pump. I2I which is driven by a driving belt I22 draws fluid I from the reservoir through a pipe I23 and forces fluid through a pipe I24 to a reverse'or control valve I25. The valve I25 is preferably of a piston type comprising valve pistons I26, I21 and parts, as illustrated. in the drawings, fluid .under. pressure passing through the pipe I24 enters a valve chamber I29 between the valve pistons I26 and'IZ'I and passes" out through a pipe I30 which conveys fluid under pressure to cylinderv chambers I3I and I32 respectively to'cause the pistons H2 and II3 to move'upwardlyinto the. position as illustrated in Fig. 1, thereby raising the upper lap I8 to an inoperative position. -.The valve I I25 is provided with a valve stem I35 which is connected to a bell crank lever I36 pivotally mounted on a stud I3'I on the column I5 of the machine. An arm ofthe bell crank I36 serves as a control lever I38 whereby the reverse valve may be readily shifted from the front of the machine. During themovement of the pistons H2 and H3 into the positions illustrated in Fig. 1, fluid is exhausted from the cylinder chambers in theupper portions of the cylinders H0 and III through a pipe I40, into a valve chamber I4I, between the valve pistons I21 and I28, and exhausts through a'pipe I42 into the reservoir I20.

produce a final or finish lapping operation; A

pressure controlling mechanism is provided so that fluid under pressure appliedto. the upper ends of the cylinders IIO andI II will cause the,

pistons H2 and H3 to exert a downward pressure on the upper lap I8 so that it is forced against the work pieces .80 at a desiredpredetermined pressure for an initial or rough lapping operation. As illustrated in the drawings, this is accomplished by providing a variable pressure regulating valve I50. This valve is connected by a pipe I5I with the fluid pressure pipe I24. The valve I50 maybe adjusted by means ofan adjusting screw I52.so that if the i pressure supplied by the pump I2I exceeds the desired pressure, a valve member I53 will be raised from its seat against the tension of a spring I54 and will allow'the excess fluid under pressure to exhaust through a pipe I55 intothe reservoir.

A second fluid pressure regulating-valve I60 is connected by a pipe I6I with-the fluid pressure pipe I24. This valve is identical with the pressure regulating valve I50 and comprises a movable valve member I62 which is held against its seat by means of a Spring I63 the tension of which may be adjusted by means of an adjusting screw I64. In setting up the machine, the pressure regulating valve I50 is adjusted to give a predetermined pressure for a rough lapping operation on the upper lap, and the pressure regulating valve I60 is adjusted to a predetermined pressure for a final or finish lapping operation.

During the normal use of the mechanism above described, the fluid pressure system is so operated that any pressure in excess of the low pressure to which the valve I60 is set would cause the valve member I62 to rise from its seat and allow the excess fluid under pressure to exhaust through a pipe I65 into the reservoir I20.

In order that either a relatively high or a relatively low pressure may be applied to the upper lapping wheel I8, a valve I10 is inserted within the pipe I6I. This valve is arranged so that in the position illustrated in Figs. 1 and 2, fluid under pressure is cut ofi from the valve I60, thus rendering the low pressure regulating valve I60 inoperative so that the upper lap will be maintained in lapping engagement with the Work at a relatively high initial or rough lapping pressure, to which the valve I50 is set. In this position of the parts, the rough lapping operation may proceed to the desired extent. When it is desired to reduce the pressure to a lower or finish lapping pressure, the valve I10 is turned through substantially ninety degrees to allow fluid under pressure to pass through the pipe I6I to the valve I 60, thus rendering the low pressure regulating valve I60 operative so that if the fluid under pressure from the pump I2I exceeds the low pressure desired for a finish lapping operation, the valve member I62 opens and allows the excess fluid under pressure to exhaust through the pipe I65 into the reservoir I20. I

It will be readily apparent from this disclosure that by manipulation of the valve I10, practically any pressure between the high and low pressure at which the valves I50 and I 60 have been set may be obtained.

It is desirable that the fluid pressure system for controlling the movement of the upper lapping wheel I8 be automatically controlled so that when the lever I 38 is shifted to start the downward movement'of the upper lap, the cycle of operation is automatically continued until the operation has been completed and the lapping element returns to its initial or inoperative position, as shown. It is desirable that the upper lap be moved automatically downward into engagement with the work with a predetermined rough lapping pressure and that the roughing pressure automatically continue for a predetermined time interval, after which the pressure of the upper lap on the work is reduced to a lower predetermined pressure for a final o-r finish lapping operation for a further predetermined time interval, after which the upper lapping element I8 is moved upwardly to an inoperative position. This cycle of operation is preferably accomplished by means of an electrical control system which is operatively connected to control the fluid pressure system to obtain the desired cycle of operation.

In the preferred construction, an electrical time delay relay I is provided. This time delay relay is arranged so that two successive adjustable time intervals may be obtained. The time delay relay I80 is connected to power lines I 8i. In the preferred construction, the time delay relay doesnot start functioning until the upper lapping wheel is in lapping engagement with the work pieces 80 at a predetermined rough lapping pressure. This is preferably accomplished by providing a normally open limit switch I82 in the circuit between the power lines and the time delay relay. The limit switch I82 is provided with an actuating roller I83 which lies in the path of an adjustable stop I84 carried by the sleeve 22. The stop I84 is adjusted so that when the upper lap I8 moves downwardly into operative contact with thework at a predeterm ned rough lapping operation, the stop screw I84 engages the roller I83 of the limit switch I82 and closes the limit switch which in turn serves to close the circuit so as to start the time delay relay I80 functioning. After a predetermined time interval, the time delay relay I80 makes a contact between the wires I 81 and I88 which serves to energize a relay I89 which closes a circuit between the contact members I90 and the relay clapper I9I which serves to close a circuit and to energize a solenoid I92 which is connected by a link I93 with the valve control lever I94 of the control valve I10. -'Ihe energizing of the solenoid I92 serves to open the valve I10, allowing fluid under pressure to pass. through the pipe I6I and to thereby automatically reduce the relatively high initial or rough lapping pressure to a predetermined. lower pressure for a final or finish lapping operation.

The finish-up lapping operation at a reduced pressure continues until the time delay relay, after a further predetermined time interval, makes a contact between the wire I81 and a wire I91 which serves to energize av relay I98. This in turn makes a circuit between the contact element I99 and the relay clapper 200 which is connected to energize a solenoid 20I which serves to shift the main control valve I25 into the position as illustrated in Figs. 1 and 2 so that fluid under pressure from the pump I2I is reversed and applied through pipe I30 to the lower cylinder chambers I3I and I32 to raise the upper lap I8 into an inoperative position, as illustrated in Fig. l.

At the same time the relay I08 is energized to close the circuit between the contact element I99 and the clapper 200, a solenoid 204 is energized. The solenoid 204 is connected by a link 205 to move the control lever 65 in a clockwise direction (Fig. 1) to shift the rod 64 toward the left, as viewed in Fig. 1, so as to disengage the clutch member 6I from the clutch member 60, thereby stopping the relative rotation of the lapping wheels I4 and I8 and also stopping the movement of the cage 8|.

When the solenoid MI is energized to reverse the flow of fluid and cause a movement of the upper lap to an inoperative position. it is desirable that this movement be at a rapid rate in order that the idle time of the machine may be reduced to a minimum. It is, therefore, desirable that the electrical control mechanism be so arranged that when the fluid under pressure is reversed, the solenoid I92 will be deenergized so as to allow the released tension of a spring 208 to close the valve I10, that is to move the lever I94 into the position as illustrated in Fig. 1,

portion of the solenoid armature 2I I. The limit switch 289 is a normally closed limit switch so that when the solenoid 28I is energized to move the parts into the position as shown in Fig. 1, the solenoid armature 2II engages the roller 2I8 and opens the limit switch 289, thereby deenergizing the solenoid I92'and allowing the released tension of the spring 288 to rapidly close the valve I18 so that the pressure applied to the cylinder chambers I3I and I32 is increased to cause a rapid idle movement of the upper lap to an inoperative position.

In lapping certain types of work, it may be desirable positively to limit the relative approaching movement between the laps I8 and A4. A fixed stop 2I5 is mounted on a fixed part of the frame of the machine and is arranged in the path of the-adjustable stop I84 carried by the sleeve 22. When the upper lap I8 is moved downwardly by the fluid pressure operated mechanism, the adjustable stop I84 engages the fixed stop surface 2I5 and positively limits the approaching movement of the lapping wheel I8. If the positive stop is used to limit the downward movement of the upper lap, the stop and the limit switch I82 are so arranged that the downward approaching movement of the adjustable stop I84 first engages the roller I83 of the limit switch before or at the time the upper lap I8 engages the'work to be lapped and an initial or rough lapping operation at a'relatively high pressure is obtained. The downward movement of the upper lap I8 continues under the relatively high pressure until] the stop I84 engages the fixed stop-2 I5 at which time the time delay relay serves to render the low pressure regulating valve operative by energizing the solenoid I92, thereby applying a relatively low pressure to the upper lap I8 which continues until .the time delay relay after a further predetermined final or finish lapping operation energizes the solenoid 28I to reverse the valve I and thereby reverse-the flow of fluid to the cylinders I I8 and I I I to rapidly separate the lapping wheels I4 and I8.

The operation of this machine is readily apparent from the foregoing disclosure. Assuming the valves and parts to have been previously adjusted to obtain the desired operating pressure, and the electrical parts have been adjusted to actuate at the desired time intervals, a plurality of work pieces 88 are inserted in a plurality of correspondingly shaped apertures in the cage 8|. The lever .85 is then moved to engage the clutch member 8| with the clutch member 88 so as to start the relative rotation of the lapping wheels I4 and I8 and also to start the rotary and gyrating movement of the cage 8I. The lever I38 is then moved downwardly to rock the bell crank I36 and to shift the valve stem I35 downwardly so that fluid under pressure from the pump I2I passing through the pipe I24 is admitted through the pipe I48 to cause a rapid downward movement of the upper lapping wheel I8. The lapping wheel I8 moves downwardly into contact with the work pieces under a predetermined pressure in accordance with the setting of the pressure regulating valve I58. When'the upper lap reaches operating contact with the work pieces 88, the adjustable stop screw I84 engaging the roller I88 01 the limit switch I82 closes the limit switch I82 and starts the electrical time delay relay I88 in operation. The rough or preliminary lapping operation at a relatively high pressure continuesfor a predetermined time interval, after which the relay I89 is rendered operative to close thecontacts I 98 and the clapper I9I to energize the solenoid I92 and simultaneously energize the solenoids 28I and 284.

The solenoid 28I serves to reverse the control valve and to reverse the flow of fiuidwithin the system to cause an upward or separating movement of the upper lap I8. At the same time the solenoid 28I is energized, the solenoid armature 2 serves to open the limit switch 289 which breaks the circuit to deenergize the solenoid I92, thereby releasing the tension of the spring 288 which closes the valve I18 so that the upper lap I8 moves rapidly to an inoperative posi-tion at a high pressure. The energizing of the solenoid 284 serves to disengage the clutch members 88 and GI and moves the braking elements "I4 and I5 into engagement with each other to stop the relative rotation of the lapping elements and the rotating and gyrating movement of the cage 8I. The workpieces 88 may then be removed from the machine and replaced with a new set of work pieces to be lapped. This cycle of operation may then be continued on successive batches of work pieces. The entire cycle of operation after the starting of the laps and shifting of the control valve is automatically controlled.

It will thus be seen that there has been provided by this invention apparatus in which the various objects hereinabove set forth together with many thoroughly practical advantages are successfully achieved. As many possible embodiments may be made of the above invention and as many changes might be made in the embodiment above set forth, it is to be understood that all matter hereinbeforeset forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

I claim:- I

1. A lapping machine of the type having a pair of opposed relatively rotatable lapping elements which are movable relatively toward and from each other and a work carrying cage therebetween, a mechanism to cause'a relative approaching and receding movement between said'lapping elements, means to control said mechanism to cause either an approaching or receding move ment between said lapping elements, a pressure regulating mechanism arranged to maintain said laps in engagement with the work at a predetermined pressure for an initialor rough lapping operation, a second pressure regulating device arranged to maintain said laps in engagement with the work at a second predetermined pressure for a final or finish lapping operation, and means to automatically change from aninitial or rough lapping pressure to a final or finish lapping pressure.

2. A lapping machine .of the type having a pair of opposed relatively rotatable lapping elements which are movable relatively toward and from each other and a work carrying cage therebe-' tween arranged to carry a plurality of work pieces through an irregular path between the operative faces of said lapping elements, a mechanism arranged to cause a relative approaching and receding movement between said lapping elements. means including a control lever arranged to cause either an approaching or receding movement between said lapping elements, means to apply a predetermined pressure for an initial lapping operation for a predetermined time interval, a second pressure regulating mechanism arranged 'to maintain the laps in engagement with the work at a second predetermined pressure for a final or finish lapping operation, and means to automatically control said pressure mechanismsso as to change from an initial to a finish lapping pressureafter a predetermined initial or rough lapping operation and to relatively separate said lapping elements aftera further predetermined finish lapping operation.

3. A lapping machine of the type having a pair of opposed relatively rotatable lapping elements which are movable relatively toward and from each other and a work carrying cage therebetween arranged to carry a plurality of work pieces through an irregular path ,between the operative faces of said lapping elements, a mechanism arranged tocause a relative approaching and receding movement between said lapping elements, means including a control lever arranged to cause either an approaching or receding movement between said lapping elements, means to apply a predetermined pressure for an initial lapping op-" eration for a predetermined time intervaL' a second pressure regulatingmechanism arranged to maintain the'laps in engagement with the work at a second predetermined pressure for a final or finish lapping operation, andan electrical time delay relay arranged automatically to control said pressure mechanisms so as to change from an initial toa finish lapping pressure after a predetermined initial or rough lapping operation and relatively to separate said lapping elements after a further predetermined finish lapping operation. I

4. In a lapping machine, opposed relatively rotatable lapping wheels and a work cage therebetween, means to cause a relative approaching and receding movement between said lapping wheels,

manually operable means to control said mechanism to cause either an approaching or receding movement between said lapping elements, a solenoid operatively connected therewith to cause a ,receding movement between said lapping elements, adjustable means to apply a relatively high pressure between the laps and work for an initial or rough lapping operation, means to apply a relatively low pressure between the laps and the work for a final or finish lapping operation, means including a solenoid to render said latter means operative, and an electrical control system including an electrical time delay relay which serves after a predetermined time interval of rough lapping to energize said second solenoid and render said low pressure device operative for a final or finish lapping operation, and to energize said first solenoid after a further predetermined time interval f finish lapping operation automatically to separate said lapping wheels.

5. A lapping machine of the type having a pair of opposed relatively'rotatable lapping elements which are movable relatively toward and from each other and a work carryingcage therebetween arranged to carry a plurality of work pieces through an irregular path between the operative faces of said laps, a fluid pressure sysments, a fluid pressure system including a control valve arranged to convey fiuidunder pressure to either end of said cylinder, a pressure regulating valve to maintain said laps in engagement with the work at a predetermined pressure for an initial or rough lapping operation, a second pressure regulating valve arranged to maintain said laps inengagement with the work at a second predetermined pressure for a finalor finish lapping operation, an adjustable stop to-limit the approaching movement of said lapping elements, and means to automatically control said pressure regulating valves soas to shift from an initial to afinal lapping pressure automatically after a predetermined initial lapping operation.

6. A lapping machine of the type having a. pair of opposed relatively rotatable lapping elements which are movable relatively toward and from each other and a work carrying cage therebetween arranged to carry a plurality of work pieces through an irregularpath between the operative faces of said laps, a fluid pressure system including a piston and cylinder which are arranged to cause a relative approaching and receding movement between said lapping elements, a fluid pressure system including a control valve to convey fluid under pressure to either end of said cylinder, a pressureregulating valve to maintain said laps in engagement with the work at a predetermined pressure for an initial or rough lapping opera tion, a second pressure regulating valve arranged to maintain the lapsin engagement with the work at a second predetermined pressure for a finish lapping operation, and a time delay relay arranged automatically to control said valves so as to change from a high to a low pressure after a. predetermined initial or'rough lapping operation and to relatively separate said lapping elements after a further predetermined finish lapping operation.

7. A lapping machine comprising opposed relatively rotatable lapping wheels and a work cage therebetween, means including a piston and cylinder operatively connected to cause a relative approaching and receding movement between said lapping wheels, a fluid pressure system including a control valve to control fluid to said cylinder, a pressure regulating valve'in said system which is adjusted for an initial or rough'lapping operation, a second pressure regulating valve which is adjusted for a final or finish lapping operation, a valve associated with said second pressure regulating valve to render it inoperative during the initial lapping operation, means including a solenoid to open saidlatter valve, and an electrical control system including a time delay relay which serves to energize said solenoid to open said valve and render the second pressure regu-v lating valve operative after a predetermined rough or initial lapping operation, to reverse said control valve to relatively separate said lapping wheels'after a further predetermined period'of finish lapping.

8. A lapping machine of the type having a pair of opposed relatively rotatable lapping elements which are movable relativelytoward'and from each other and a work carrying cage therebetween arranged to carry a plurality of work pieces through an irregular path between the operative faces of said laps, a fluid pressure system including a piston and cylinder which are arranged to cause a relative approaching and receding move ment between said lapping elements, means including a control valve to convey fluid under pressure to, either end of said cylinder, a pressure regulating valve. arranged to maintain'the laps in engagement with the work at a predetermined pressure for an initial or roughlapping operation, anormallyinoperative second pressure reg ulating valve arranged to maintain said laps in engagement with the work at a second predetermined pressure for a final or finish lapping operation,'and an electrical control system including a time delayrelay which is operatively connected automatically to render said second pressure reg-1 ulating valve operative afterthe initial or rough lapping operation has continued for a predetermined time interval and automatically to sepa-, rate said lapping elements after the final. or finish lapping operation has continued for a further predetermined time interval. l

y 9. A lapping machine of the type having a pair ofopposed relatively rotatable lappingelements which are movable relatively toward and from each other, a work carrying cage arranged to carry a plurality of work pieces for a simultaneous lapping operation between said laps, means including a fluid pressure piston and cylinder operatively connected to move one of said laps relatively toward and from the other, a fluid pressure system including a control valve, anadjustable pressure regulating valve in-said system to obtain a predetermined pressure between said laps and work pieces for aninitial lapping operation, a second adjustable pressure regulating valve which is adjusted to causesaid laps to lap the work at a second predetermined pressure for afinal lapping operation, and an electrical control system including a rendered effective when the laps move into operative engagement with the work to allow the rough or initial lapping operation to proceedfor a pre determined' time interval, after which the second pressureregulating valve is rendered operative, and to thereafter automatically shift said control valve to separate said lapping elements after the final or finish lapping-operation has proceeded for a-further predetermined time interval.

10. In a lapping machine, opposed relatively rotatable ,lappingwh'eels and a work cage therebetween,-means including a piston and cylinder operatively connected to cause a relative approaching and receding movement between said lapping wheels, a fluid pressure systemincluding a control valve to control the flow of fluid to and from said cylinder, manually operable means to shift said valve to causeeither an approaching or a receding movement of said lapping wheels, an

electrical solenoid which is arranged to shift said i control valve to cause a receding movement between said lapping elements, a pressure regulating valve which is adjusted for-an initial or rough lapping operation, a second pressure regulating valve which is adjusted for a final or finish lapping operation, said second pressure regulating valve being inoperative during the rough lapping operation, a solenoid to render said secondvalve operative,'and an electrical control-system including a time delay relay which is rendered operative when the lapping wheels approach the work pieces and which serves after a predetermined time interval of rough lapping to energize the time delay relay which is second solenoid to render the second pressure regulating valve operative to produce a predetermined'pressure for a final or finish lapping operation, and after a furtherpredetermined time interval of finish lapping to energize said first solenoid toshift the control valve and thereby to cause a relative separating movement of said laps.

ll.- A lapping machine of the type having a pair of opposed relatively rotatable lapping elements one of which is movable relatively toward and from the other, a work cage therebetween for simultaneously supporting a plurality of work pieces for asimultaneous lapping action between the opposed faces of said laps, means comprising a pair of spaced fluid pressure cylinders arranged on diametrically opposite sides ofthe axis of the movable. lap, pistons within said cylinders which are operatively connected to cause a relative approaching and receding movement betweensaid laps, a fluid pressure system including a control valve arranged to simultaneously, admit. fluid under pressure to either end of said cylinders, a pressure regulating valve in said system which is arranged to regulate the pressure of fluid so as to cause the laps to be maintained in engagement with the work at apredetermined pressure for an initial lapping operation, a second pressure regulating valve in said system to maintain the laps in lapping engagement with the work at a second predetermined pressure for a, finish lapping operation, and means including an electrical time delay relay arranged to automatically render said first pressure regulating valve inoperative after a predetermined time interval. J

12. A lapping machine of the type having a pair of opposed relatively rotatable lapping elements one of which is movable relatively toward and from the other, a work cage therebetween for simultaneously supporting a plurality of work pieces for a simultaneous lapping operation be tween the opposed faces of said laps, and means comprising a pair of spaced fluid pressure cylinders arranged on diametrically opposite sides of the axis. of the movable lap, pistons within said cylinders which are operatively connected to cause a relative approaching and receding movement between said laps, a fluid pressure system including a control valve arranged to simultaneously admit fluid under pressure to either end of said cylinders, a pressure regulating valve in said system which is arranged to regulate the pressure of the fluid so" as to cause the laps to be main-- tained in engagement with the work at a predetermined pressure'for an initial lapping operation, a second pressure regulating valve in said system which is arrangedto be adjusted to maintain the laps in lapping engagement with the work at a second predetermined pressure'for a finish lapping operation, and an electrical control 7 shift the main control valve after a final or finish lapping operation for a further predetermined time interval to separate the lapping elements from engagement with the work.

,. v RAYMOND A. COLE. 

